Drafting instrument.



G. E. OLTM'AN. DRAWING INSTRUMENT. APPucATmM mm Am. 11. ms.

Patented NW. 2?, 1911?,

2 SHEETS-SHEET 2- v lmmm INVENTOR fl m ATTORNEY ITNE SSES' GEORGE E. OLTMAN, or SHELIBYVILLE, INDIANA.

DRAFTING INSTRUMENT.

Specification of Letters Patent.

Patented Nov. 2?, ldll't.

Application filed April 17, 191.6. S'eriaIi'No. SL658.

To all whom it may concern:

Be it known that I, Gnonon E. OLTMAN, a citizen of the United States, residing at Shelbyville, in the county of Shelby and State of Indiana, have invented certain new and useful Improvements in Drafting Instruments, of which the following is a specification.

This invention has relation to mechanical. drafting instruments, and the nature and objects thereof will be readily apparent to those skilled in the art to which it appertains, in the light of the following explana tion of the accompanying drawings, illustrating what I now believe to be the preferred embodiment or mechanical expression of my invention from among other forms and arrangements within the spirit thereof or the scope of the appended claims.

However, an object of the invention is to provide a drawing board and T-square to be associated therewith whereby the T- square may be moved along the board during the course of preparing a drawing, and whereby the T-square may be secured against displacement in any position.

Another object of the invention is to provide means in a T-square for moving the same along the edge of a drawing board intermittently, and for uniform distances for use in drawing a series of paralleled lines, an occasion frequently occurring during the preparation of a mechanical drawing.

Another object of the invention is to provide a T-square and an associated guide which may be attached to the edge of an ordinary drawing board.

A still further object of the invention is to provide a T-square associated with a drawing board, and whereby the T-square may be thrown back so as to give uninterrupted view of the drawing board, and

whereby the T-square when returned to its former position retains the same relative position to the drawing or delineations thereon.

In addition to the foregoing my invention comprehends improvements in the details of construction and arrangement of parts, to be hereinafter described and particularly pointed out in the appended claims.

In the accompanying drawings in which similar and corresponding parts are designated by the same characters of reference throughout. the: several. views in which they appear:

, Figure. l is a fragmentary plan view of: a. drawing board. and a. T-squareapplied thereto, constructed after the fashion of my invention.

Fig. 2 is a detail section taken on the line 22 of Fig. 1.

Fig. 3 is a detail view in perspective of a cl1p for attaching the guide to a board.

Fig. 4 is a plan view of the mechanism contained Within the head of the T-square, with the cover plate removed.

Flg. 5 is an edge view of the T-square head.

Fig. 6 is an edge elevation thereof.

Fig. 7 is a section taken on the line 77 of Fig. 4, and

Fig. 8 is a fragmentary view of the guide.

lVith reference to the drawings, 1 indicates a drawing board, to one edge of which is secured a guide 2, which is in the form of a hollow rectangle in cross section and having two sets of flanges 3 and 4:, a flange being formed at. each corner of the rectangle, and the flanges of each set oppositely extended. The flanges 3, are engage-able by the curved edges 5, of a clip 6 which is adapted to be secured to the edge of a drawmg board by means. of a lag screw or the like 7.

A T-square head is provided which. is in the form of substantially semi-circular mating plates 8 and 9, having flanges to dispose them in spaced relation and removably secured together by threaded fastenings 10. The diametrical edges of the semi-circular plates are formed with inwardly extending flanges 11, which are adapted to engage the flanges i of the guide 2, so as to dispose the outer surface of the guide within the head of the T-square, the flanges 4 of the guide being movable in recesses 12, at opposite ends of the head.

A lever 13, in the form of spaced bars connected at either end, is pivoted at one of its ends to a pivot 14.- within the head of the T- square, the lever being thereby disposed between the plates of the head. A to thed wheel 15 is mounted between the bars of the lever 13, and upon a rivet 16 connecting both bars, a washer 17 being disposed upon. the rivet at each side of the toothed. wheel to centralize the same. A plurality of; opentlti ings 18 vare formed in the outer surface of the guide 2 in which openings the teeth of the wheel are designed to engage. A leaf spring 19, is secured to the lever adjacent its pivoted end, with the other end of the spring engaging the wall of the head to urge the lever inward and consequently retain the H toothed wheel in engagement with the guide. Ifurther provide a stud 2O rotatably mounted in the head and extending transversely thereto, and having on the interior of the head an'arm 2l, flexibly connected to the stud may be rotated,'so as to oscillate its arm 21 and thereby rotate the lever about its fulcrum and thereby disengage the toothed wheel from the guide to permit quick adjustment of the head along the guide, or for purposes of assembling the device. 7

A lever 23 is provided, and having spaced terminals 2% which are provided with alined apertures for pivotal engagement upon the rivet 16, with one of the arms at either side of the wheel 15. A lever 2% is pivoted at 25 between the arms or" the lever 23 and is provided at one end with a pivoted pawl 26, having a serrated concaved face 27 adapted to engage the teeth of the wheel 15. The other end of the lever 2-l is pivotally connected by means of links 28, to a grip 29,

pivoted between ears 30 formed on the side of the lever 23. A leaf spring 31 is further provided and extends from between the ears 30, to the end of the lever 24:, against which it bears. Owing to this arrangement the pawl 26 is normally retained out of engagement with the wheel 15, and may be readily brought into such engagement by pressing the handle portion of the grip 29 toward the I handle portion or" the lever 23.

. Apertured lugs are provided upon the upper surface of the T-square head for the pivotal support or" a hinged member 33, having an apertured enlargement 3+l disposed between the lugs 32, with a pintle 35 passing through said lugs and the enlargement. The hinged member 33 is provided with an aperture 36 which, when the hinged member is in operable position should be disposed at the center defined by the circular edge of the T-square head. A T-square blade 37 is secured at one end to an extension 38, which is provided with an aperture 39, adapted to register with the aperture 36 of the member 33. A washer 4L0 is further provided with an aperture adapted to register with the apertures 39 and 36, and an extension 41 whereby said washer may be secured to the enlargement 3% and be disposed above the extension '38. The aperture of the hinged member 33, is preferably internally threaded, and a thumb nut 42"is provided having a threaded shank which iflange ati being formed on said thumb nut whereby the member 38 may be clamped between the member 33 and-the washer A0 to retain the T-square blade in any position to which it may be adjusted relative to the head; This arrangement provides in elfect a T-square having a swiveled head;

' In operation, should the draftsman desire to draw a series of parallel lines, the lever 23 is grasped, andthe grip 29 moved so as to apply the pawl 26 to the edge of the wheel 15 whereupon oscillating said lever 23, and releasing the grip 29at each'backward oscillation, the head of theT-square is causedto travel along the gu'ide2 in an obvious manner. The uniformity of the spacing of the lines may be established by noting the movement of the lever 23 in connection with graduations a l inscribed on the face of one of the plates forming the head, and at the circular edge thereof, The angle of the blade of the T-square may be varied by loosening the thumb nut 42, and rotating the blade about the pivot formed by the shank of said thumb nut which may slightest degree its original relation to any of the lines of the drawing. If the metallic parts of this device are to be composed of aluminum, the total weight thereof may be materially reduced. j

Various ways of constructing my invention will occurto those skilled in the art to which it appertains, for the purpose of employing the principlesinvolved therein, and I therefore reserve the right and privilege of changing the form of the details of construction, or otherwise altering the arrangement of the correlated parts without departing from the spirit of the invention or the scope of the appended claims. p 1 Having thus'describedmy invention'what I claim as new and desire to secure by Let ters Patent is 1. A drafting device comprising in comfor engaging the notchesof the guide, re-

silient means engaging the lever 'to retain the wheel in engagement with the guide,"

means for oscillating the'lever to move thel30 wheel out of such engagement, and means for rotating the wheel to move the head along the guide.

2. A drafting'device comprising in combination a drawing board, a guide mounted upon one edge thereol and having a series of notches, a T-square head movably mounted upon the guide, a blade secured to the head and extending over the board, a Wheel journaled upon the head and having peripheral teeth for engaging the notches of the guide, a lever pivotally mounted upon the guide, a pawl on the lever adapted to engage the wheel, resilient means for normally retaining the pawl out of such engagement, means on the lever for moving the pawl into engagement with the wheel whereby the wheel may be rotated by oscillating the lever, resilient means for retaining the wheel in engagement with the guide and means for moving the wheel out of such en agement.

3. A drafting device comprising in combination a drawing board, a guide mounted upon one edge thereof and having a series of notches, flanges formed on the outer surface or the guide, a T-square head substantially semi-circular in configuration and comprising spaced plates, inwardly directed flanges on the diametrical edges of the plates for engaging the flanges of the guide to afford movement of the head along the guide, a toothed wheel mounted between the plates for engaging the notches of the guide,

means for rotating the wheel, and a blade secured to the head and extending over the board.

4. A T-square including a head, upstanding lugs on the head, a member hingedly mounted between the lugs for rotation in one plane and a blade pivoted to the member for movement in a plane at right angles to the plane of movement of the member, and means for securing the blade against displacement subsequent to said movement.

5. A T-square including a head, upstanding lugs on the head, a member hingedly mounted between the lugs for rotation in one plane, a clamping member mounted upon the first mentioned member in spaced relation, alined apertures provided in said members, a blade having an apertnred extension at one end for engagement in the space between the members, and thumb screw extending through the apertures and having a flange for engaging the clamping member to permit of adjustment of the blade in a plane at right angles to the plane of movement of the first mentioned member and for securing the blade against displacement subsequent to such adjustment.

In testimony whereof I aflix my signature in presence of two witnesses.

GEORGE E. OLTMAN.

Witnesses:

HARRY C. RAY, H. C. KINNEY.

Copies of this patent may be obtained for five cents each. by addressing the Commissioner of Patents, Washington, D. C. 

